Ch1-3 Hearts in Canon (aka Canon of Youth)
Due to family matters, Hanada quits playing the music instrument he has been playing since high school and is living through one boring day after the next, until he runs into Hashizaki when attending the brass band reunion on a whim... He can't believe it when the once-serious Hashizaki shows up wearing a flashy suit... Hanada doesn't like the person he's become, gets drunk and takes it out on Hashizaki. But not only does Hashizaki passionately steal a kiss from him, he tells Hanada he's liked him since high school...! Passionate love unfolds between the flashy but loyal top and the bottom who has difficulty communicating with others. This manga also includes

Ch4-5 Trumpet of Melancholy (aka Melancholy Melody)
The bittersweet love between two high schoolers in the brass band club. The happy-go-lucky Kai is desperately inviting his fellow club member, Takara to perform a trumpet duet with him. At first, Takara, who does not like doing bothersome things, kept avoiding Kai. But when he finally started to tear down his heart wall, he accidentally heard about Kai's crush?

Note: The Renta! version contains a tiny bonus chapter called, "Memories"